New diagnostic approach for ocular tuberculosis by ELISA using the cord factor as antigen.
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BACKGROUND/AIMS: Diagnosis of ocular tuberculosis is difficult, particularly the retinal vasculitis type, because most cases occur without concurrent active pulmonary tuberculosis. Recently, it has been reported that detection of antibodies against purified cord factor (trehalose-6,6'-dimycolate, TDM), the best studied, most antigenic, and most abundant cell wall component of tubercule bacilli, is very useful for rapid serodiagnosis of pulmonary tuberculosis. In this study, an attempt was made to evaluate whether the detection of anticord factor antibody is also useful for diagnosis of ocular tuberculosis and the necessity of antituberculous therapy for tuberculous retinochoroiditis was discussed. METHODS: Cases consisted of 15 patients with uveitis and retinal vasculitis, nine patients with presumed ocular tuberculosis, three patients with sarcoidosis, and three patients with Behcet's disease. IgG antibodies against purified cord factor prepared from Mycobacterium tuberculosis H37Rv were detected by enzyme linked immunosorbent assay. RESULTS: All cases of clinically presumed ocular tuberculosis were positive, whereas all of the cases of sarcoidosis or Behcet's disease were negative for anticord factor antibodies. When the anticord factor antibody titres were compared on the basis of the presence or absence of previous antituberculosis chemotherapy, the mean anticord factor antibody titre of the untreated group showed a tendency to be higher than in the treated group, but not significantly (p=0.07). CONCLUSIONS: The detection of anticord factor antibody may be useful to support the diagnosis of ocular tuberculosis. Additionally, a positive result for anticord factor antibody may indicate that tubercule bacilli are present in some organ(s) of the patient even in the absence of active systemic disease. (+info)
Experimental retinal branch vein occlusion in rhesus monkeys. I. Clinical appearances.
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Branch and hemisphere vein occlusion were produced in rhesus monkeys by argon laser photocoagulation. The following observations were made: (1) Immediately after occlusion there was venous dilatation, delayed filling of the artery, delayed drainage by the occluded vein, and capillary leakage. (2) Two patterns of evolution were identified within the first week. In some animals the fundus changes resolved and the retina returned to normal, while in others there was progressive retinal capillary closure. (3) Those animals destined to have capillary closure had diffuse or cluster retinal haemorrhages at 24 hours. (4) Capillary closure took place over 1 week and was usually complete over large areas of retina. (5) Retinal atrophy and major vessel changes occurred over several weeks. (6) Retinal revascularisation occurred in those areas of closure, though this was often limited. It was concluded that the early changes mimicked those seen in human retinal vein occlusion, though persistent retinal oedema and preretinal neovascularisation were not identified. (+info)
Experimental retinal branch vein occlusion in rhesus monkeys. II. Retinal blood flow studies.
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Experimental branch vein occlusion by laser photocoagulation in the rhesus monkey leads to early, marked, and lasting reduction of blood flow to the affected retinal region. The radioactive microsphere method demonstrates this reduction of blood flow in both gamma counting and autoradiography. The reduction of flow becomes evident as early as 2 hours after occlusion and persists up to 1 week. The mechanism of the altered flow is discussed. (+info)
Experimental retinal branch vein occlusion in rhesus monkeys. III. Histopathological and electron microscopical studies.
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Experimental retinal vein occlusion in monkeys was followed by an immediate increase in capillary permeability which was accompanied by retinal oedema. This functional capillary change was followed at about 6 hours after occlusion by structural damage to the capillary wall. Thrombus formation occurred in the damaged vessels, and areas of stasis were thus produced with associated retinal haemorrhages. Finally, there was complete loss of the capillary endothelium and pericytes, and the acellular capillaries were invaded by proliferating glial cell processes, so producing permanent capillary closure. (+info)
RI in central retinal artery as assessed by CDI does not correspond to retinal vascular resistance.
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The aim of the present study was to investigate the association between ultrasound Doppler measurements of resistive index (RI) in the central retinal artery and retinal vascular resistance (R) assessed with laser Doppler velocimetry, vessel size measurement, and calculation of ocular perfusion pressure (PP) in healthy subjects. An increase in vascular resistance was induced by inhalation of 100% O(2). During hyperoxia no significant changes in PP were observed. Mean flow velocity in main retinal veins was reduced by -27.5 +/- 2.0%. The average decrease in diameter was -11.5 +/- 1.0%. R, which was calculated as the ratio of PP to flow rate, increased by 97.6 +/- 7.7%. RI increased as well, but the effect was much smaller (6.6 +/- 2.2%). In addition, a negative correlation was found between baseline values of R and RI (r = -0.83). During hyperoxia R and RI were not associated. In conclusion, our data indicate that RI as assessed with color Doppler imaging in the central retinal artery is not an adequate measure of R. (+info)
The effect of arterial PO2 on relative retinal blood flow in monkeys.
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The relationship of blood oxygenation to retinal blood flow has been studies in rhesus monkeys. Constriction of major retinal arteries and veins during hyperoxia and dilation during hypoxia are demonstrated. Together with mean circulation times based on the technique of fluorescein densitometry curves, these data allow an estimation of retinal blood flow, which increases considerably in hypoxia and shows a moderate decrease in hyperoxia. These findings indicate that the retinal circulation parallels that of the brain in adjusting to changes in arterial PO2 with compensatory changes in blood flow. (+info)
Excitation and emission spectra of fluorescein dye in the human ocular fundus.
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The excitation and emission spectra of fluorescein dye were determined during angiography from different sites in the human ocular fundus. All spectra were markedly shifted toward longer wavelengths relative to the spectra of fluorescein in aqueous solution. This effect is most pronounced for the macular area; however, it decreases for the choroidal background and even more for the retinal vessels. The results are relevant to the selection of optical filter combinations for fluorescein angiography. (+info)
Study of the distribution of retinal blood vessels in buffaloes (Bos bubalis).
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The distribution of retinal blood vessels in the eye of buffalo was studied macroscopically and microscopically in twenty-two eyes of healthy animals. After macroscopic observation, 12 of 22 eyes were used for histological study. Ten eyes were stained with hematoxylin and eosin and two eyes with PAS stain. The present findings revealed that the eye of the buffalo was characterized by the complex network of retinal blood vessels (holangiotic or euangiotic). The central retinal artery and vein pierced the eye through the optic disc and gave off several branches. There were four pairs of primary vessels that were named dorsal, ventral, nasal and temporal retinal arteries and veins. The veins anastmosed with each other at the optic disc to form a somewhat circle. Three patterns of the distribution of blood vessels were described. The distribution of the arteries and veins was the same. (+info)